CDAP-539: Ported DictionaryOpsApp to use Services instead of Procedures.

Initial commit of etl-pack-app migration to services instead of procedures.
Retrieves a value from a dictionary for a specific key. Request should be formatted using this pattern:\<br>
\<code>get/{dictionary-name}/{dictionary-key}/{dictionary-field}/{key-type}\</code>

@param request HTTP service request
@param responder HTTP service responder
@param dictName Name of dictionary where value must be searched
@param dictKey Key for search
@param dictField Field of dictionary
@param type Type of key. Supported types: <code>STRING, INT, DOUBLE, FLOAT, LONG.</code>
            See {@link FieldType} for list of supported types.
@throws IOException

See next comment about changing "type" to "keyType"